A high-level delegation representing the Organization for African Unity warned the Reagan administration yesterday that African nations are running out of patience waiting for South Africa to grant Namibia independence.

After a two-hour meeting with Secretary of State Alexander M. Haig Jr., however, the African ministers refrained from direct criticism of President Reagan's policy, enunciated over the weekend by Assistant Secretary of State Chester A. Crocker, of not trying to undermine South Africa "in order to curry favor elsewhere."

Kenyan Foreign Minister Robert Ouko, speaking for the OAU group, also avoided criticism of the United States for its stand on the current South African invasion of Angola. Ouko called the South African thrust "naked aggression," but did not attack the United States, which cast a veto in the United Nations yesterday to block a resolution condeming the South African invasion.

Ouko told reporters at the Kenyan Embassy that "Haig told us the United States is committed to implementation" of the U.N. resolution calling for independence for Namibia. "We must take him at his word," he said.

"All I can say is we have had a frank exchange of views," Ouko said when pressed to characterize his meeting with Haig.

A State Department official said Haig explained U.S. reasons for not condemning the South African invasion alone in keeping with a general policy of "seeking to persuade South Africa on Namibia instead of trying to coerce it, as the Carter administration did."

He added, "The jury, of course, is still out on our effort."

Although black African leaders have spoken in the past of seeking economic sanctions against South Africa because of its foot-dragging on Namibia, Ouko raised no threat of sanctions.

He referred to "the desperate situation surrounding Namibia" and said Namibians are suffering "human indignities of untold proportions," but spoke of no future measures to aid Namibian independence except for the special session of the U.N. General Assembly that begins Thursday and is the next stop on the itinerary of the delegation that visited Haig.

The United States was the last of the five western nations seeking a peaceful route to Namibian independence that the delegation visited. Ouko said the delegation undertook its trip to West Germany, France, Britain, Canada and the United States because it had a message to deliver: " . . . That the African continent is impatient over this delay."

It was these five western nations that asked black Africa to wait for their attempt at negotiations with South Africa, he reminded reporters. "We accepted because our countries are weak and poor," Ouko said.

The Reagan administration has been less willing to antagonize South Africa than the Carter administration was, and critics have said its approach has encouraged South Africa to further delay arranging for Namibian independence, which the United Nations demanded in a 1978 resolution.

Control over Namibia (also known as South-West Africa) was given to South Africa by the United Nations after World War I. Namibia is overwhelmingly black and is the last large African land area that is not independent.

U.S. officials have said they are working with the other western nations on new proposals to present to the parties to the Namibian dispute.

Ouko said Haig had not told the delegation details of these measures. "We are waiting to know more about these so-called confidence-building measures . . . and whose confidence they are supposed to boost," Ouko said.

Black African nations fear the measures would aid the white minority to maintain its privileged position in Namibia, a mineral-rich territory.

Crocker, in his speech, which was designed to pull together U.S. policy toward the region, said: "In South Africa, the region's largest country, it is not our task to choose between black and white. In this rich land of talented and diverse peoples, important western economic, strategic, moral and political interests are at stake."

Ouko took clear exception to two aspects of the evolving U.S. policy. He said Angola is not part of the Namibian problem, although the United States cites the presence of Cuban troops in Angola as one element to be deplored in the region.

And while Reagan has referred to SWAPO (the South-West Africa People's Organization) as a terrorist group, Ouko rejected that characterization. "SWAPO is the sole representative of the people of Namibia," he said.